The apache point observatory lunar laser-ranging operation (apollo) is potentially capable of performing two-way laser ranging to the lunar reconnaissance orbiter (LRO), using the array of twelve…

The apache point observatory lunar laser-ranging operation (apollo) is potentially capable of performing two-way laser ranging to the lunar reconnaissance orbiter (LRO), using the array of twelve corner cube reflectors placed on the zenith-facing side of the spacecraft. If successful, the range measurements would: 1) establish sub-centimeter constraints on the location of LRO with respect to the exquisitely-well-determined locations of the laser reflectors on the moon. In so doing, this would: 1A) provide a calibration of the LRO clock, more rigorously than the one-way ranging campaign is capable of doing; 1B) provide a firm reference for laser altimetry of the lunar surface, which will operate simultaneously to the two-way ranging; 2) answer questions about the health of the 40-year-old reflectors on the lunar surface by comparison of signal strengths; 3) represent the farthest-ever two-way laser ranging to a spacecraft. Apollo has already invested significant resources into preparing for successful two-way ranging. This includes new hardware to enable a wider detector gate, software to create time-of-flight predictions, tracking paths, velocity aberration point-ahead displacements, etc. In addition, the observatory has developed the software to allow the telescope to track arbitrary paths on the sky. Aside from the preparatory work, carrying out the observations requires continued resources. The observations are performed by russet mcmillan, requiring two hours of effort for each hour spent on the sky. Two aircraft spotters are required to protect airplanes from accidental illumination, at 1.5 hours of effort per hour of observation. And finally, the telescope is operated by the astrophysics research consortium (ARC), based on financial support from a number of universities. The equivalent operational cost of running the telescope is $1,116 per hour of scheduled time. Since ranging to LRO is external to ARC, this charge must be borne by external funds. In total, we request $50,942 to support 40 hours of telescope time in pursuit of successful two-way ranging. A discounted rate of $1,000 per hour of telescope time, together with support for 80 hours of mcmillan's time, and 120 hours of spotter support adds to $49,520. The additional $1,422 is in support of russell owen's time to incorporate changes to the telescope control software to allow tracking of paths on the sky described by chebyshev polynomials. We anticipate a direct subcontract between the goddard space flight center (gsfc) and ARC, spanning from september 2010 to december 2012. The long span permits optimal choice of observing opportunities, which come in groups of a half-dozen or so nights spread across two months, recurring every six months. Telescope scheduling constraints, together with constraints imposed by the LRO mission operations center (MOC) do not allow US to utilize every favorable opportunity. A several-year span is necessary to provide ample opportunity for success.